A prior art suspension front fork is shown in FIG. 6 and generally includes a lower tube 81 and an end of an upper tube 82 which is movably inserted into the lower tube 81. Hydraulic oil is filled in the lower tube 81 and a chamber 85 is defined above the oil level in the upper tube 82. A valve assembly 84 seals a top of the upper tube 82 so as to keep the pressure in the chamber 85 higher than the atmosphere. A damper assembly 86 is fixed to a lower end of the upper tube 82 and located in the lower tube 81. The damper assembly 86 is submerged in the hydraulic oil and includes a passage 861. A piston 862 is received in the damper assembly 86 and an outlet 863 is defined through a top of the damper assembly 86. A spring 864 is received in the damper assembly 86 and pushes the piston 862 to be located at a lower position in the damper assembly 86. When the bicycle rides on terrain roads, to absorb shocks and vibrations the upper tube 82 is moved toward the lower tube 81 and oil in volume 83a is displaced and passes through damper assembly 86 to volume 83 to absorb a terrain bump. As the bump passes, upper tube 82 moves away from lower tube 81 and oil from volume 83 passes through passage 861 driven by air pressure in volume 85 returning to volume 83a. The action of the fork is dependent on several factors including the viscosity of the hydraulic oil, temperature, pressure in the chamber 85, size of the orifice in passage 861, etc. Additionally, there are rider preferences for the action of the fork and the prior art suspension fork allows only pressure adjustment as an external rider adjustment of the fork action.
The present invention intends to provide an additional means for adjustment of the suspension wherein the damping forces can be modified by rotating an adjusting ring on top of the front fork. This, along with the pressure adjustments, allows the rider to “tune” the suspension to a desired action and compensate for external factors like temperature.